iommufd: Reject non-zero data_type if no data_len is provided

Since the current design doesn't forward the data_type to the driver to
check unless there is a data_len/uptr for a driver specific struct we
should check and ensure that data_type is 0 if data_len is 0. Otherwise
any value is permitted.

Fixes: bd529dbb661d ("iommufd: Add a nested HW pagetable object")
Link: https://lore.kernel.org/r/0-v1-9b1ea6869554+110c60-iommufd_ck_data_type_jgg@nvidia.com
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/drivers/iommu/iommufd/hw_pagetable.c b/drivers/iommu/iommufd/hw_pagetable.c
index 3f3f1fa1a0a946a43eb48ee324ab4979683bb566..33d142f8057d70a77f44e842afdd84b1bee0a970 100644 (file)
--- a/drivers/iommu/iommufd/hw_pagetable.c
+++ b/drivers/iommu/iommufd/hw_pagetable.c
@@ -263,7 +263,8 @@ int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd)
 
        if (cmd->__reserved)
                return -EOPNOTSUPP;
-       if (cmd->data_type == IOMMU_HWPT_DATA_NONE && cmd->data_len)
+       if ((cmd->data_type == IOMMU_HWPT_DATA_NONE && cmd->data_len) ||
+           (cmd->data_type != IOMMU_HWPT_DATA_NONE && !cmd->data_len))
                return -EINVAL;
 
        idev = iommufd_get_device(ucmd, cmd->dev_id);